Methods and apparatus for joint distraction

ABSTRACT

A method of treating a patient&#39;s joint having opposing joint surfaces includes providing an elongate member having a proximal end, a distal end and an expandable member near the distal end. The expandable member is positioned in the joint between the joint surfaces and expanded so as to separate the joint surfaces away from one another into a distracted position. The joint is manipulated while in the distracted position so that the joint is distracted and in flexion. A diagnostic or therapeutic procedure is then performed on the joint while maintaining the joint in the flexed and distracted position.

REFERENCE TO PENDING PRIOR PATENT APPLICATIONS

This patent application is a division of pending prior U.S. patentapplication Ser. No. 12/483,446, filed Jun. 12, 2009 by David Boudreaultet al. for METHODS AND APPARATUS FOR JOINT DISTRACTION, which in turn is(i) a non-provisional of, and claims the benefit of priority under 35USC 119(e) of prior U.S. Provisional Patent Application Ser. No.61/061,457, filed Jun. 13, 2008 by Vivek Shenoy et al. for DEVICES ANDMETHODS TO DISTRACT AND TREAT JOINTS, and (ii) a non-provisional of, andclaims the benefit of priority under 35 USC 119(e) of prior U.S.Provisional Patent Application Ser. No. 61/164,604, filed Mar. 30, 2009by Vivek Shenoy et al. for METHODS AND APPARATUS FOR JOINT DISTRACTION

The above-identified patent applications are hereby incorporated hereinby reference.

STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSOREDRESEARCH AND DEVELOPMENT

Not applicable.

REFERENCE TO A “SEQUENCE LISTING,” A TABLE, OR A COMPUTER PROGRAMLISTING APPENDIX SUBMITTED ON A COMPACT DISK

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present disclosure relates to medical devices and methods, and morespecifically to methods and devices used to distract joints including,but not limited to the hip, shoulder, ankle, and wrist joint. Jointdistraction enables introduction of therapeutic or diagnosticinstruments into the joint space so that various medical procedures maybe performed on the joint.

Arthroscopy is a minimally invasive surgical procedure used in theexamination and treatment of joint disease or damage. While arthroscopictreatment of the knee and shoulder joints is common today, fewerarthroscopic procedures are performed in other joints such as the hip,ankle and wrist joint due to challenges associated with accessing thejoint space.

In the case of the hip joint, it is the deepest and largest joint in thebody. The hip joint is formed between the head of the femur and theacetabulum and is a very difficult joint to separate. This is due inlarge part to a blanket of ligaments and tendons that cover the joint,forming a tight sealed capsule. Additionally the acetabular labrum, afibrocartilaginous lip, surrounds the head of the femur, deepening thejoint pocket and increasing the surface area of contact. The labrumdivides the hip joint into two compartments within the joint capsule:central and peripheral. The central compartment is within the confinesof the labrum and contains the majority of the articular cartilage andthe ligamenturn teres, a ligament attached to a depression in theacetabulum (the acetabular notch or fossa) and a depression on thefemoral head (the fovea of the head). The peripheral compartment is thespace outside the labrum and within the capsule.

In order to provide access to a joint space for a diagnostic ortherapeutic procedure, the joint often must be distracted. Distractionis the term used to define a combination of traction and distention usedto separate the joint, which in the case of a hip joint, allows thesurgeon to access the central compartment. This is typicallyaccomplished by positioning a patient on a distraction table andapplying forces of 50-70 pounds to the patient's foot while the pelvisis constrained by a post positioned against the perineum. The tractionis maintained as long as access to the central compartment is needed.

This external method of joint distraction is not without challenges andcan result in complications. The most common complications are thetransient neuropraxias of the sciatic, lateral femoral cutaneous andpudendal nerves. Additionally, pressure applied to the foot and perineumduring distraction can result in pressure necrosis of the skin andunderlying tissue, as well as vaginal and anal tears. Problems withlacerations to the lateral femoral cutaneous nerve can also occur, whichleaves permanent numbness to the anterior thigh. Additionally, oncetraction is applied to the joint, it is difficult to further manipulatethe joint to alter joint position or provide increased access to thejoint space since distraction tables often have rigid arms or fixturesthat must be locked into position. Further, because traction tables relyon the application of tensile force to the foot, the knee cannot be bentwhile traction is maintained. While some traction tables permit somedegree of flexion, abduction, or adduction while traction is applied,because the knee must be straight, the degree of such manipulation issubstantially limited. Flexion in particular is limited to less than 20°due to the potential risk of sciatic nerve damage.

Moreover, when traction is applied to a joint, tension in adjacenttissue often increases, further increasing difficulty of accessing thejoint space. In the case of the hip joint, application of tractionresults in increased tension in the ligaments and tendons of the capsulewhich further inhibits introduction and manipulation of arthroscopicinstruments in the joint space. It would therefore be desirable toprovide devices and method that overcome some or all of thesechallenges.

Arthroscopy in the ankle and wrist also require distraction for accessinto certain joint areas. However, unlike the hip, the distractionforces aren't high, ranging from 10-30 lbs. Nevertheless, distraction ofthe ankle and wrist share similar challenges to treatment as the hipjoint.

Balloon catheter technology has been widely adopted in cardiovascularapplications and is now also being used in other areas includingorthopedic applications such as kyphoplasty and otolaryngologyapplications like sinuplasty. The use of balloons for internaldistraction of a joint has been proposed. For example, Aydin et al. hasreported the use of a kyphoplasty balloon to distract an ankle jointwhile Sartoeretti has disclosed the use of angioplasty balloons forankle distraction. U.S. Pat. No. 6,017,305 to Bonutti discloses the useof an inflatable bladder to retract bones and U.S. Pat. No. 6,616,673 toStone discloses a method of separating a hip joint with a device havingseveral expandable spheroid regions. While some of these devices andmethods appear to be promising, they are not without challenges. Forexample, using existing balloons which are often small sized may requireexcessive pressures to achieve the necessary distraction force and inthe case of the hip joint, existing balloons may not distract the jointsurfaces enough (e.g. at least about 10 to 12 mm) to allow access forother surgical instruments. Other devices may be inflatable to anappropriate size but they may also occupy too much of the joint spacelimiting access for instruments. Further because these devices mayengage a wide area of the joint, they may also limit joint manipulation.Moreover, some the disclosed devices also still require externaldistraction in order to initially place the device into the joint due totheir large unexpanded profile.

In view of these challenges, it would be desirable to provide improveddevices and methods for distracting joints such as the hip, ankle,shoulder and wrist joint, as well as other joints. Such methods anddevices preferably would be cost effective, easy to manufacture andsimple to use. Furthermore, such methods preferably have lowercomplication rates than existing distraction methods and devices andalso provide easy and wide access to the joint space without requiringexternal traction. In addition to distracting the joint, such methodsand devices preferably allow easy introduction of other diagnostic ortherapeutic instruments into the joint space. Moreover, the methods anddevices preferably also allow the joint to be manipulated while in thedistracted position in order to allow increased access to the joint oraccess to other regions of the joint space. Some or all of theseobjectives will be met by the devices and methods disclosed herein.

2. Description of the Background Art

Scientific publications of interest in connection with the presentinvention include Burman, M. S., Arthroscopy or the direct visualizationof joints: an experimental cadaver study. 1931. Clin Orthop Relat Res,2001 (390): p. 5-9; Tan, V., et al., Contribution of acetabular labrumto articulating surface area and femoral head coverage in adult hipjoints: an anatomic study in cadavera. Am J Orthop, 2001. 30(11): p.809-12; Dienst, M., et al., Hip arthroscopy without traction: In vivoanatomy of the peripheral hip joint cavity. Arthroscopy, 2001. 17(9): p.924-31; Shetty, V. D. and R. N. Villar, Hip arthroscopy: currentconcepts and review of literature. Br J Sports Med, 2007. 41(2): p.64-8; discussion 68; Sartoretti, C, et al., Angioplasty BalloonCatheters Usedfor Distraction of the Ankle Joint. Arthroscopy: TheJournal of Arthroscopic and Related Surgery, 1996. 12(1), Feb.: p.82-86;and Aydin, A., et al., A New Noninvasive Controlled Intra-articularAnkle Distraction Technique on a Cadaver Model. Arthroscopy: The Journalof Arthroscopic and Related Surgery, 2006. 22(8), Aug.: p.905.e-905.e3;

Patents of interest in connection with the present invention include EP507645 and U.S. Pat. Nos. 7,226,462; 6,616,673; 6,017,305; 5,290,220;and 4,467,479. Patent publications of interest include U.S. PatentPublication Nos. 2009/0112214; and 2006/0293685 and PCT Publication Nos.WO 2007/080454; and WO 00/23009.

BRIEF SUMMARY OF THE INVENTION

The present invention generally relates to medical methods and devices,and more specifically to methods and devices used to distract jointsincluding, but not limited to the hip, ankle, shoulder, knee and wristjoints. Joint distraction enables introduction of therapeutic ordiagnostic instruments into the joint space so that other medicalprocedures may be performed on the joint.

In a first aspect of the present invention, a method of treating apatient's joint having opposing joint surfaces comprises providing anelongate member having a proximal end, a distal end and an expandablemember near the distal end. The expandable member is positioned in thejoint between the joint surfaces and expanding the expandable memberseparates the joint surfaces away from one another into a distractedposition. While the joint surfaces remain in the distracted position,the joint is manipulated into a manipulated configuration in which thejoint is in both flexion and distraction. A diagnostic or therapeuticprocedure is performed on the joint while maintaining the joint in themanipulated configuration. In some embodiments, the expandable membermay be positioned in the joint without applying external tractionthereto.

Positioning may comprise advancing the expandable member over aguidewire or through a cannula into the joint which may be a hip joint.The hip joint has an acetabular fossa, and the step of positioning maycomprise advancing the expandable member through a cannula extendinginto the joint capsule. The expandable member may remain in the fossa asit is expanded. The hip joint also has an acetabulum and a femoral headcoupled together with a ligamentum teres, and the expandable member maybe positioned posterior to the ligamentum teres. In some embodiments, aretention mechanism may be deployed from the cannula in order to anchorthe cannula into the joint.

Expanding the expandable member may comprise inflating a balloon. Theballoon may be inflated to a pressure not exceeding about 100 psi andthe balloon may exert at least about 25 pounds of force against thejoint surfaces. The expandable member may engage each joint surfacewithin a contact area no more than about 800 square millimeters. Eachjoint surface has a total area, and the expandable member may engageeach joint surface within a contact area no larger than about 50% of thetotal area and more preferably less than about 30% of the total areawhen the expandable member is expanded. The balloon has an outer surfacewith a radius of curvature when expanded and the radius of curvature maybe about 8-18 mm. When the joint is a hip joint having a total jointsurface area of the acetabulum outside the fossa, the balloon maycontact one of the joint surfaces along a contact area, and preferablyno more than about 50%, and more preferably less than about 30% of thetotal joint surface area is contacted by the balloon or expandablemember when expanded. Expanding the expandable member may separate thejoint surfaces at least about 10 mm away from one another. Also,expanding the expandable member may fluidly isolate a portion of thejoint from the remainder of the joint. Balloon position may be adjustedwithin the joint in order to change the joint separation.

Manipulating the joint may further comprise one or more of flexion,extension, lateral rotation, medial rotation, abduction and adduction ofthe joint. The joint may be placed in up to about 20 degrees of flexion,up to about 30 to 80 degrees of abduction, and/or up to about 10 to 30degrees of adduction. When the joint comprises a hip joint, a capsulesurrounds the joint and manipulating the hip joint reduces tension inthe joint capsule which makes it easier for a device to be insertedthrough the capsule and under the labrum. One or more instruments may bepositioned through the relaxed portion of the joint capsule while thetension is reduced in order to perform a diagnostic or therapeuticprocedure. Manipulation of the joint may be performed while theexpandable member is expanded.

Performing the diagnostic or therapeutic procedure may comprisearthroscopically viewing the joint. The diagnostic or therapeuticprocedure may also comprise one or more of labral repair or debridement,lavage, osteotomy, microfracture or chondral repair of the jointsurfaces or tissue adjacent thereto. Tissue adjacent the joint may alsobe distended by infusion of fluid into the tissue, such as the hip jointcapsule.

The joint may be a hip joint and the step of manipulating the joint mayfurther comprise bending a knee ipsilateral to the hip joint. The hipjoint may be maintained in the manipulated and distracted configurationwith a brace that is releasably coupled with the patient's leg that isipsilateral to the hip joint. After the expandable member has beenexpanded, the method may further comprise contracting the expandablemember and actively reducing profile of the contracted expandablemember. A stylet may be positioned in a lumen in the elongate memberduring the advancing step. Also a portion of the elongate member may beactively deflected into a curved configuration. Expanding the expandablemember may comprise inflating a balloon with an inflation medium that isstored in a reservoir of an inflation device. A switch on the inflationdevice may be actuated so as to deliver a predetermined volume ofinflation medium from the reservoir to the balloon thereby expanding theexpandable member which may be a balloon. In some embodiments theexpandable member may be detachably coupled with the elongate membersuch that the elongate member may be detached from the expandable memberwhile seated in the joint or fossa of the joint in an expandedconfiguration. Sometimes, a spacer may be inserted into the joint afterexpansion of the balloon or expandable member, or after the joint hasbeen separated.

In another aspect of the present invention, a hip joint comprises anacetabulum, an acetabular fossa and a femoral head and a method oftreating a patient's hip joint comprises providing an elongate memberhaving a proximal end, a distal end and an expandable member near thedistal end. The expandable member is advanced into the hip joint betweenthe femoral head and the acetabulum and positioned into the acetabularfossa. The expandable member is expanded thereby separating the femoralhead from the acetabulum while the expandable member remains in theacetabular fossa. A diagnostic or therapeutic procedure is thenperformed on the hip joint while the expandable member is expandedwithin the acetablular fossa.

The expandable member may have an axial length that is no more thanabout 1.3 times the diameter of the expandable member when expanded. Adistal portion of the elongate member may be substantially more flexiblethan a proximal portion of the elongate member. The elongate member maycomprise a distal tip that extends a distance no more than about 10 mmfrom a distal end of the expandable member.

The distal end may extend distally of the expandable member and thedistal end may be slidably advanced through and beyond the acetabularfossa without traumatic engagement with tissue therein. The acetabulumhas a curvature and a distal portion of the elongate member may have acurvature in an unbiased condition selected to follow the curvature ofthe acetabulum as the distal portion is advanced. Advancing may beperformed without applying external traction.

Positioning the expandable member may comprise advancing the expandablemember over a guidewire or through a cannula extending into the jointcapsule. The acetabulum and the femoral head are coupled together by aligamentum teres, and the expandable member may be positioned posteriorto the ligamentum teres.

Expanding the expandable member may comprise inflating a balloon. Theballoon may be inflated to a pressure not exceeding about 100 psi. Theballoon may exert at least about 25 pounds of force against the femoralhead and the acetabulum when inflated. The expandable member may engagethe femoral head and the acetabulum within a contact area that is nomore than about 800 square millimeters. The hip joint comprises a totaljoint surface area of the acetabulum outside the fossa and the ballooncontacts the joint surface along a contact area no more than about 50%,and more preferably less than about 30% than total joint surface areawhen the balloon is expanded. Expanding the expandable member separatesthe femoral head and the acetabulum at least about 10 mm away from oneanother. Expanding the expandable member may also fluidly isolate aportion of the hip joint from the remainder of the hip joint.

Performing the diagnostic or therapeutic procedure may comprisearthroscopically viewing the hip joint. Viewing the joint may includeviewing the acetabulum or the femoral head posterior to the expandedexpandable member. Diagnostic or therapeutic procedures may comprise oneor more of labral repair, debridement, flushing, smoothing,microfracture, or chondral repair of the femoral head, the acetabulum oradjacent tissue. The method may also include distending a capsulesurrounding the hip joint before advancing the expandable member.Distension may be accomplished by infusing fluid into the capsule.

The hip joint may be manipulated while the femoral head and theacetabulum remain separated from one another so that the hip joint is ina manipulated and a distracted configuration. The hip joint may be inflexion while in the manipulated and distracted configuration. Thetherapeutic or diagnostic procedure may be performed while the hip is inthe manipulated and distracted configuration.

In still another aspect of the present invention a hip joint has anacetabulum and an acetabular fossa and an apparatus for distracting ahip joint comprises an elongate flexible member having a proximal endand a distal end and an expandable member coupled with the elongatemember near the distal end. The expandable member is expandable from acollapsed configuration to an expanded configuration and the expandablemember has a transverse dimension of at least about 10 mm in theexpanded configuration and also has an expanded shape and expanded sizeselected so that the expandable member seats in the acetabular fossa.

The expandable member may be configured to apply a radial force of atleast 50 pounds when expanded to a pressure of no more than 100 psi. Theexpandable member may be configured to engage a portion of the the totalsurface of the acetabulum outside of the fossa only within a contactsurface, and the contact surface is no more than about 50%, andpreferably less than about 30% of the total surface when the expandablemember is in the expanded configuration. The joint surface is the totalsurface area of the acetabulum outside the fossa. The expanded size andthe expanded shape may be selected so that the expandable member isbiased into the fossa when expanded. The expandable member may have anouter surface with a radius of curvature of at least about 8 mm in theexpanded configuration. The expandable member may have an axial lengthin the expanded configuration that is no more than about 1.5 times thewidth of the acetabular fossa. The expandable member may also have anaxial length that is no more than about 0.8 to about 1.3 times thediameter of the expanded expandable member when expanded. The contactsurface of the expandable member may be at least about 200 squaremillimeters and less than about 800 square millimeters. The flexiblemember may comprise at least one lumen extending between the proximaland distal ends.

The expandable member may comprise a balloon. Some of the possibleshapes of the expandable member include generally, dome shaped,spherical, a flat inferior side with a semi-spherical superior side, ora central bulbous region with an annular region surrounding the bulbousregion. The expandable member may comprise at least two expandableregions, with each region being expandable independently of the other.Other expandable member configurations include having a distal taperdifferent than the proximal taper. The distal taper may be steeper thanthe proximal taper. The proximal taper may be in the range of about 10to about 45 degrees and the distal taper may be in the range of about 30to about 90 degrees. Sometimes the proximal and distal tapers areopposite and thus the distal taper may be in the range of about 10 toabout 45 degrees and the proximal taper may be in the range of about 30to about 90 degrees. The expandable member may comprise an invaginatedend fixedly attached with the elongate member.

The expandable member may have a toroidal region and the elongate membermay be coupled with a lateral portion of the toroidal region such that alongitudinal axis of the elongate member is substantially perpendicularto a central axis of the toroid. The toroidal region may have an opencentral region and the elongate member may comprise one or moreapertures near the distal end opening into the central region to allowegress of fluid or tools therefrom into the center of the toroid. Theexpandable member may comprise surface features that are adapted tofacilitate retention of the expandable member in the acetabular fossa.Some of these surface features may include projections, bumps, ridges,and sticky regions. The expandable member may also comprise a lubriciouscoating adapted to facilitate withdrawal of the expandable memberthrough a sheath. The expandable member may further comprise a punctureresistant layer of material.

The apparatus may further comprise means for collapsing the balloon. Themeans for collapsing the balloon may comprise a shaft rotationallyengaged with the expandable member such that the shaft is adapted torotate and collapse the expandable member. The means for collapsing theballoon may also comprise a linearly actuatable shaft coupled with theexpandable member such that the shaft is adapted to stretch theexpandable member into a flattened configuration. The expandable membermay be expanded with a fluid having a refractive index, and theexpandable member may be composed of a material having a refractiveindex substantially the same as the refractive index of the fluid. Theexpandable member may also comprise a coating adapted to enhancetranslucency or reduce reflection of light. The apparatus may furthercomprise a fiber optic filament disposed in the elongate member fortransmitting light from a light source.

The elongate member may comprise a distal tip adapted to be passed intoand through the hip joint without causing trauma to the joint or tissueadjacent thereto. The distal tip may have a curvature with a radius nolarger than a curvature of the acetabulum so that the distal tip isbiased away from the acetabular surfaces as the elongate member ispassed into and through the hip joint. The distal tip may extend no morethan about 10 mm from a distal end of the expandable member. The distaltip may comprise various shapes including substantially straight,conical, curved, J-shaped, and pigtail shaped. The distal tip may alsocomprise a tapered region. The tapered region may be on two opposingsides so as to be more flexible about one transverse axis than about asecond transverse axis. The distal tip may be resilient and biased toreturn to a predefined unbiased shape.

The elongate member may comprise a curved region in a distal portion ofthe elongate member and the curved region may have a radius within ±20%of the radius of the acetabulum. The apparatus may further comprise astylet removably disposed in a lumen of the elongate member and that isadapted to straighten the elongate member during advancement of theelongate member into the hip joint. The stylet may be removably disposedin a lumen of the elongate member in order to increase columnar strengthof the elongate member. The stylet may be disposed in a lumen of theelongate member and it may have a curved portion that is adapted to forma corresponding curve in the elongate member. The stylet may comprise aplurality of parallel slots transverse to the longitudinal axis of thestylet in order to allow bending of the stylet. The parallel slots maybe disposed only on a first side of the stylet such that the styletbends more easily in a first direction than in a second direction. Thestylet may also have a cross-sectional width that is greater than itscross-sectional height so that the stylet bends more easily in a firstdirection than in a second direction. The elongate member may alsocomprise a distal nosecone and a stylet disposed in a lumen of theelongate member. The nosecone often is conical, but one of skill in theart will appreciate that other configurations are possible and may benon-conical. The stylet may be keyed to the nosecone such that rotationof the stylet rotates the nosecone. Rotation of the stylet may rotate adistal end of the expandable member relative to a proximal end of theexpandable member.

The elongate member may comprise a guidewire lumen. The elongate membermay comprise a distal guidewire port and a proximal guidewire port, eachmay be sized to allow passage of a guidewire slidably therethrough andthe proximal guidewire port may be disposed proximal to the expandablemember and closer to the distal end of the elongate member than theproximal end. The apparatus may also comprise a guidewire at leastpartially disposed in the elongate member and a stopping element may becoupled with the guidewire. The stopping element may be adapted toconstrain advancement of the guidewire into the elongate member.

The elongate member may comprise a cross-sectional geometry selected toallow bending around one transverse axis of the elongate member moreeasily than around other transverse axes. This geometry may include anoval, racetrack, and rectangular shape. The elongate member may have awidth along a first transverse axis substantially greater than a heightof the elongate member taken along a second transverse axis orthogonalto the first axis. The elongate member may comprise one or more lumens,and the elongate member may be biased to collapse to a flattenedconfiguration when the one or more lumens are evacuated.

The apparatus may further comprise a pullwire disposed in a lumen of theelongate member and operably coupled with a distal portion of theelongate member such that actuation of the pullwire forms a curve in thedistal portion of the elongate member. The elongate member may comprisea distal tip extending distally of the expandable member and the curveis formed only in the distal tip. The apparatus may also have anactuator mechanism near the proximal end of the elongate member that isoperably coupled with the pullwire. The apparatus may have a shieldpositionable over at least a portion of the expandable member and theshield may be able to prevent puncture of the expandable member.

In another aspect of the present invention, a medical apparatuscomprises an inflatable member positionable in a body cavity and havingan interior. An elongate flexible shaft has a proximal end, a distalend, an inflation lumen extending therebetween, and a cross-sectionalheight. The distal end of the shaft is coupled with the inflatablemember and the inflation lumen is in fluid communication with theinterior of the inflatable member. The shaft comprises a collapsedprofile and an expanded profile and the cross-sectional height in thecollapsed profile is substantially less than the cross-sectional heightin the expanded profile. Also, the shaft is biased to remain in thecollapsed profile.

The cross-sectional height in the expanded profile may be at least abouttwice the cross-sectional height in the collapsed profile. A stylet maybe slidably and removably disposed in a stylet lumen of the shaft. Theshaft may have a first column strength when the stylet is removed fromthe stylet lumen and a second column strength when the stylet isdisposed in the stylet lumen. The second column strength may besubstantially greater than the first column strength. Passage of aninflation fluid through the inflation lumen to the interior of theinflatable member may expand the shaft from the collapsed profile to theexpanded profile. The shaft comprises a cross-sectional width, and inthe collapsed profile the cross-sectional width may be substantiallygreater than the cross-sectional width in the expanded profile. Thecross-sectional width may be greater than the cross-sectional height inboth the expanded and collapsed profiles. The shaft also comprises alongitudinal axis and an axis transverse thereto, and the shaft may beconfigured to bend about the transverse axis more easily than at leastone other transverse axis.

The inflatable member has an inflated shape and inflated size selectedso that when inflated within a hip joint, the inflatable member may seatin an acetabular fossa of the hip joint. When inflated to a pressureless than about 100 psi, the inflatable member may be adapted to apply apressure of at least 50 pounds. The inflatable member has a contactsurface for engaging the surface of the acetabulum outside the fossa,and no more than 50%, and more preferably less than about 30% of theacetabular surface outside the fossa is contacted when the when theinflatable member is inflated.

In still another aspect of the present invention, a medical apparatuscomprises an inflatable member positionable in a body cavity and havingan interior. An elongate flexible shaft has a proximal end, a distal endand an inflation lumen extending therebetween. The distal end of theshaft is coupled with the inflatable member and the inflation lumen isin fluid communication with the interior of the inflatable member. Theshaft has a longitudinal axis and a first axis transverse thereto andthe shaft bends substantially more easily about the first transverseaxis than about at least one other transverse axis.

The shaft has a cross-sectional height and a cross-sectional width. Thecross-sectional height may be substantially less than thecross-sectional width. The cross-sectional shape may includerectangular, oval, and racetrack shapes. The inflatable member has aninflated shape and an inflated size selected so that when inflatedwithin a hip joint, the inflatable member may seat in an acetabularfossa of the hip joint. When inflated to a pressure less than about 100psi, the inflatable member may be adapted to apply a pressure of atleast 50 pounds. The inflatable member has a contact surface forengaging the acetabulum of the hip joint and no more than 50%, andpreferably less than 30% of the total surface of the acetabulum outsidethe fossa is contacted by the inflatable member when inflated.

In another aspect of the present invention, a system for distracting ajoint surrounded by a joint capsule comprises an inflatable memberhaving an interior and an elongate flexible shaft coupled with theinflatable member. The shaft has an inflation lumen in fluidcommunication with the interior of the inflatable member and aninflation unit is coupled with the shaft. The inflation unit comprisesan inflation fluid reservoir fluidly coupled with the inflation lumen, adisplacement mechanism for delivering fluid from the reservoir into theinflation lumen, and a controller. The controller has a switch andactuation of the switch causes movement of the displacement mechanismthereby delivering a predetermined volume of inflation fluid to theinterior.

The inflatable member has an inflated volume that may be selected todistract the joint by a desired distance and the predetermined volumemay be equal to the inflated volume. Actuation of the switch causesmovement of the displacement mechanism thereby evacuating inflationfluid from the interior. The displacement mechanism may comprise a motorand a power supply electrically coupled therewith. The switch maycomprise an electronic switch. The predetermined volume may be at least16 mL and the inflation unit may be adapted to deliver the predeterminedvolume at pressures up to 200 psi. The inflation fluid may comprisesaline, contrast media or combinations thereof. The predetermined volumemay be selected to incrementally or fully inflate the inflatable memberin a single step. The system may also include a distraction sensor thatis adapted to indicate the amount of joint distraction. The system mayhave a guidewire and the elongate flexible shaft is advanceable over theguidewire to the joint.

Sometimes the joint comprises a hip joint having an acetabular fossa andthe inflatable member has an inflated shape and an inflated sizeselected so that when inflated, the inflatable member may seat in anacetabular fossa of the hip joint. When inflated to a pressure less thanabout 100 psi, the inflatable member is adapted to apply a pressure ofat least 50 pounds. The inflatable member has a contact surface forengaging the acetabulum of the hip joint and no more than about 50%, andpreferably less than about 30% of the total acetabular surface outsidethe fossa is contacted by the inflatable member when inflated.

In another aspect of the present invention, a system for distracting ajoint comprises an inflatable member having an interior and an elongateflexible shaft coupled with the inflatable member. The shaft has aguidewire lumen and an inflation lumen in fluid communication with theinterior of the inflatable member. The system also includes anarthroscopic instrument adapted to diagnose or repair the joint.

The instrument may include one of a retractor, a cutter, a debrider, asuture anchor, and a grasper. The system may also include a guidewirethat is at least partially disposed in the elongate shaft and a stoppingelement may be coupled with the guidewire. The stopping elementconstrains advancement of the guidewire into the guidewire lumen. Thesystem may include a shield device positionable at least partially overthe inflatable member. The shield may be adapted to prevent puncture ofthe inflatable member.

In yet another aspect of the present invention, a system for distractinga joint surrounded by a joint capsule comprises an elongated cannulahaving a central channel therethrough with a distal end positionable inthe joint capsule and a retention mechanism for holding the cannula inthe joint capsule. The system also includes a distraction device. Thedistraction device has an elongated shaft and an expandable balloon nearthe distal end of the shaft. The balloon is positionable through thecentral channel. The distraction device is configured to be insertedthrough the central channel and into the joint to hydraulically distractthe joint.

The retention mechanism may be attached to the cannula. The retentionmechanism may be coupled to a second shaft positionable through thecentral channel. The retention mechanism may comprise a radiallyexpandable portion of the cannula or a plurality of resilient filamentsthat are biased to flare radially outward when unconstrained by thecannula. The retention mechanism may be configured to engage an inner orouter surface of the joint capsule. The retention mechanism may have aninner portion that is positionable within the joint capsule and an outerportion that is positionable outside the joint capsule. The cannula maycomprise two halves that may be separated from one another.

These and other embodiments are described in further detail in thefollowing description related to the appended drawing figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the anatomy of a hip joint.

FIG. 2 illustrates distraction of a hip joint under traction.

FIG. 3 illustrates a top view of a hip joint.

FIGS. 4A-4G illustrate balloon distraction of a hip joint.

FIGS. 5A-5C illustrate various balloon contact areas.

FIG. 6 illustrates a support for maintaining joint distraction.

FIG. 7 illustrates various axes of movement about the hip joint.

FIG. 8 illustrates use of a leg brace to hold a patient's distracted hipin a desired position.

FIGS. 9A-9I illustrate another embodiment of balloon distraction of thehip joint.

FIGS. 10A-10B illustrate balloon distraction vectors.

FIGS. 11A-11E illustrate various embodiments of distraction balloons andcontact areas.

FIG. 12 illustrates another exemplary embodiment of a distractionballoon.

FIGS. 13A-13C illustrate another exemplary embodiment of a distractionballoon.

FIGS. 14A-14B show another exemplary embodiment of a distractionballoon.

FIGS. 15-20 show still other exemplary embodiments of a distractionballoon.

FIGS. 21A-21C illustrate yet another exemplary embodiment of adistraction balloon.

FIGS. 22A-22B illustrate another exemplary embodiment of a distractionballoon.

FIGS. 23A-23B illustrate still another exemplary embodiment of adistraction balloon.

FIGS. 24, 25A-25B, 26A-26B, 27A-27C and 28A-28B show other exemplaryembodiments of distraction balloons.

FIGS. 29A-29C illustrate various surface features on a distractionballoon.

FIG. 30 illustrates an optional fiber optic light source in combinationwith a balloon distraction catheter.

FIG. 31 illustrates a sensor in the distraction balloon.

FIGS. 32A, 32B and 32C illustrate various embodiments of low profiledistraction balloons.

FIG. 33 illustrates an actuator mechanism.

FIG. 34 illustrates another embodiment of a low profile distractionballoon.

FIG. 35 illustrates another actuator mechanism.

FIG. 36 illustrates another embodiment of a low profile distractionballoon.

FIGS. 37A-37B illustrate yet another embodiment of a low profiledistraction balloon.

FIGS. 38A-38B illustrate an exemplary embodiment of a distractionballoon tip.

FIGS. 39A-39C illustrate another embodiment of a distraction balloontip.

FIGS. 40A-40B illustrate yet another embodiment of a distraction balloontip.

FIGS. 41, 42A-42B and 43 illustrate other distraction balloon tips.

FIGS. 44A-44C illustrate several embodiments showing use of a guidewirewith a distraction balloon.

FIGS. 45A-45C illustrate use of a stylet.

FIG. 45D illustrates a slotted shaft.

FIGS. 46A-46B illustrate various shaft configurations.

FIGS. 47A-47B illustrate deflection of the shaft.

FIGS. 48A-48B and 49A-49B illustrate protection of a distractionballoon.

FIGS. 50A-50B illustrate a detachable balloon.

FIG. 51A-51B illustrate another embodiment of a separable balloon.

FIG. 52 illustrates a distraction balloon inflator.

FIG. 53 illustrates a distraction balloon kit.

FIG. 54A-54E illustrate cannula retention mechanisms.

FIGS. 55A-55B, 56 and 57 illustrate various embodiments of cannulas.

DETAILED DESCRIPTION OF THE INVENTION

The methods and devices disclosed in this specification will bediscussed mainly in terms of exemplary embodiments involving the hipjoint. One of skill in the art will of course appreciate that thesemethods and devices may be used on other joints including but notlimited to the shoulder, ankle or wrist joint, and that disclosure ofhip joint distraction is not intended to be limiting.

FIG. 1 illustrates the basic anatomy of a hip joint. In FIG. 1 the hipjoint is formed between the head of the femur FH and the acetabulum A, aconcave surface of the pelvis. The acetabular fossa AF is a recessedregion in the acetabulum. A blanket of ligaments cover the joint forminga capsule C. Additionally the acetabular labrum, a fibrocartilaginouslip, surrounds the head of the femur, deepens the joint pocket andincreases the surface area of contact. The labrum L divides the hipjoint into two compartments within the joint capsule: a centralcompartment CC and a peripheral compartment PC. The central compartmentCC is within the confines of the labrum L and contains the majority ofthe joint cartilage and the ligamentum teres LT, a ligament attached toa depression in the acetabulum (the acetabular notch or fossa) and adepression on the femoral head (the fovea of the head). The peripheralcompartment PC is everything outside the labrum. The central compartmentCC is not visible until the joint has been distracted.

FIG. 2 illustrates how traction 204 is conventionally applied to thepatient's leg and against a post 202 positioned against the perineumregion to distract the femoral head FH away from the acetabulum Athereby creating a space 206 between the two joint surfaces. This space206 allows a surgeon to access the joint and perform diagnostic ortherapeutic procedures. However, conventional distraction tables areoften rigid systems affixed to an operating room table and they are noteasily adjustable. Thus, once distraction is obtained, conventionaldistraction tables are locked into position to maintain the distractionand have very limited capability for further manipulation of the jointto provide greater access to the joint or access to different regions ofthe joint space. For example, in the case of a hip joint, it would bedesirable to be able to flex, extend, abduct, adduct, laterally rotateor medially rotate the joint through a broad range of motion so thataccess and visibility to the joint space and adjacent structures may beadjusted while the joint is distracted. In addition, even withdistraction tables that allow some manipulation of the hip joint,because traction must be maintained, it is not possible usingconventional distraction tables to bend the patient's knee. When the legis straight, the hip joint may be flexed up to approximately 20°, butbending the knee allows the hip joint to be flexed even more, therebyallowing even greater access to the joint. Additionally, the pressureexerted by the post 202 against the perineum can result in postoperative complications and therefore it would be desirable to provideimproved methods and devices for distraction of joints.

In order to overcome the challenges of current distraction techniques,the present invention provides methods and apparatus for internaldistraction of a joint that do not require external traction to beapplied. In preferred embodiments the invention provides a hydraulicdistraction device, e.g. a balloon, that may be placed into the interiorof the joint between the opposing bones and inflated with a fluid todistract the joint. FIG. 3 illustrates some of the possible entryportals for delivering a balloon to the hip joint. FIG. 3 is a top viewof a hip joint in which the femoral head FH rests against the acetabulumA. The joint space is covered by the capsule C and the labium L. Accessto the hip may be obtained by introducing a balloon in a posterolateralportal PLP along a side and posterior to the joint or an anterolateralportal ALP along a side and anterior to the joint. The balloon andrelated instruments may be delivered into the joint space through a portor cannula, or using minimally invasive techniques such asSeldinger-like or percutaneous introduction, or a cutdown procedure maybe used. FIGS. 4A-4E illustrate how access to the hip joint may beobtained.

Percutaneous access to the hip joint begins with a needle such as a 17gauge needle (not illustrated) advanced through the skin and past thecapsule C into the joint space 406. This may be observed underfluoroscopy or other imaging systems. The capsule is then optionallydistended by injecting saline into the space. Once the needle is inplace, a guidewire GW or switching wire is advanced through the needleinto the joint space. The needle is then withdrawn, leaving theguidewire GW in place. The guidewire GW serves as a rail over whichother instruments may be delivered to the joint space. In FIG. 4A, atubular sheath or cannula 402 having a tapered end 408 is advanced overthe guidewire GW into the joint space 406. The tapered end 408 helps thesheath to pass through and penetrate layers of the capsule C. A ballooncatheter (FIG. 4C) is nested inside sheath 402 and the sheath constrainsthe balloon in order to help keep balloon profile to a minimum as wellas to provide protection to the balloon during delivery. Optionally, inFIG. 4B a syringe with needle 404 or other injection device may be usedbefore, during or after delivery of the balloon catheter to inject fluidsuch as saline into the joint space in order to help distend the capsuleC, thereby creating additional working space and facilitating passage ofthe guidewire and/or catheter through the capsule. Breaking the sealcreated by the labrum and introducing fluid pressure into the centralcompartment also helps to distract the joint sufficiently to allowinsertion of balloon catheter 412. The sheath 402 carries a catheter 412with deflated balloon 414 into the joint space as seen in FIG. 4C. Oncethe sheath 402 is positioned, the catheter 412 having deflated balloon414 on its distal end may be advanced through the sheath and exposed (oralternatively, the sheath may be retracted) as seen in FIG. 4D. Thedistal end of the catheter may have an atraumatic distal tip 416 that isadapted to facilitate advancement of the catheter around the curvedjoint space without causing damage to the articular cartilage orsurrounding tissues. Additionally, the balloon 414 is advanced andpositioned posterior to the ligamentum teres LT without causing damageto the ligament or associated tissues. In other situations, it may bedesirable to position the balloon anterior to the ligamentum teres andin still other situations a forked balloon may be used to pass on bothsides of the ligamentum teres (as disclosed below). The balloon 414 isthen expanded with saline, contrast media, a combination of the two, oranother fluid may be used including gaseous inflation fluids. This maybe seen in FIG. 4E. Once expanded, the balloon distracts the femoralhead FH away from the acetabulum A, increasing the joint space 406.Balloon expansion is performed without causing damage to the ligamentumteres, nearby vasculature, nerves, or other adjacent tissues.Preferably, the balloon will create a gap of about 10 to 12 mm or more.An arthroscopic instrument 410 may then be advanced into the joint spacethrough the same cannula or a different cannula, so that diagnostic ortherapeutic procedures may be performed on the joint or surroundingtissues.

In preferred embodiments, the balloon is advanced into the joint andexpanded so that when expanded, it seats in the acetabular fossa AF. Theacetabular fossa is a concave region in the acetabulum and provides anatural concavity into which the balloon may be seated to stabilize theballoon and inhibit its movement as it expands and as the joint ismanipulated. FIG. 4F more closely illustrates seating of an expandedballoon in the acetabular fossa. The balloon remains seated in the fossaduring inflation and distraction of the joint. FIG. 4G is a view of theacetabulum A and the fossa F looking into the joint space with thefemoral head removed. The balloon 414 indicated by dotted lines isseated in the fossa with minimal overlap onto the surrounding surface ofthe acetabulum. Additionally, while the balloon is inflated and thejoint is distracted, the hip may be manipulated in order to alter jointposition and increase access to the joint space as will be discussed ingreater detail below.

Preferably, the area of the balloon that contacts the joint surfaceswill be minimized in order to allow maximum visibility of, and access tothe joint tissues. At the same time, because the distraction forceprovided by the balloon is the product of the balloon contact area andthe balloon pressure, sufficient contact area must be provided in orderto avoid excessively large balloon pressures. FIG. 5A illustrates thesituation where contact area is minimized. In FIG. 5A, a sphericallyshaped balloon 3906 near the distal end of a shaft 3908 is inflated inthe joint space between the acetabulum A and the femoral head FH. Thespherically shaped balloon 3906 is inflated and contacts the jointsurfaces at a point of contact 3902 on the acetabulum A and also a pointof contact 3904 on the femoral head FH. This provides relativelyunobstructed access to the joint space. However, because the contactarea 3902, 3904 is very small, the balloon pressure will be very high inorder to provide adequate force to distract the joint. Preferably, theballoon will be constructed of a generally inelastic, non-distensiblematerial such that the balloon may be inflated to a fixed volume. FIG.5B illustrates what happens when such a balloon is inflated. The contactareas 3902 a, 3904 a of the balloon 3906 a flatten out and conform tothe joint surfaces as the balloon expands. Because the balloon flattensout, access to the joint space is more limited than in FIG. 5A, yetbecause the contact area 3902 a, 3904 a is greater, lower balloonpressures are required to distract the joint. FIG. 5C illustrates anembodiment that balances the balloon contact area with joint access. InFIG. 5C a cylindrically shaped balloon 3906 b is coupled to a shaft 3908and advanced to the joint space between the acetabulum A and the femoralhead FH. The cylindrical body of the balloon 3906 b provides arelatively large flat upper contact area 3902 b and a relatively largeflat lower contact area 3904 b that engage the acetabulum A and femoralhead FH, respectively. The contact areas 3902 b, 3904 b are sufficientlylarge so that reasonable balloon pressures may be employed duringdistraction while at the same time, still allowing relativelyunobstructed access to the joint space. Preferably the total area ofcontact of the balloon against each joint surface will be no more thanabout 50% of the total area of that joint surface. In the case of thehip joint, the contact area is preferably no more than about 50%, andmore preferably less than about 30% of the total surface area of theacetabulum outside the fossa, when the balloon is inflated.

In a preferred embodiment, the balloon contacts the acetabulum over atotal contact area no more than about 800 mm², and preferably thecontact area is no more than about 50%, and more preferably less thanabout 30% of the surface area of the acetabulum outside the fossa whenthe balloon is inflated. On the other hand, the balloon contact areawill not be so small that extremely high pressures are required todistract the joint, thereby requiring balloons with extremely high burstpressures. In preferred embodiments the balloon is capable of generatingsufficient force to distract the joint, preferably generating at least30 pounds of force and more preferably at least 50 pounds of force, andmost preferably at least 75 pounds of force with pressure not exceedingabout 20 atmospheres (300 psi), more preferably not exceeding about 7atmospheres (100 psi), and most preferably not exceeding about 5atmospheres (75 psi). Thus, in preferred embodiments, the total contactarea of the balloon on each of the opposing joint surfaces will be about0.3 to 1.2 square inches (200 to 800 mm²). Additional balloonembodiments are disclosed below. Because of these desired operatingconditions, most commercially available balloon catheters would not besuited for distracting a joint. In particular, cardiovascular balloonswould generally not be able to distract the joint as far as desired atsufficiently low pressures. Moreover, often, many of the commerciallyavailable balloons are very long and therefore would not fit properly inthe joint space, would not seat securely in the fossa, or they wouldobstruct the work field or they could be ejected from the joint duringinflation.

After the joint has been distracted, a spacer 4202 as illustrated inFIG. 6 may be placed in the joint space in order to maintain separationof the joint surfaces after the balloon distraction device has beenremoved. The spacer 4202 includes an upper surface 4204 that has acurvature matching that of the acetabulum A and a lower surface 4206that has a curvature matching that of the femoral head FH. Having amatching contour helps prevent damage to the joint surfaces and moreevenly distributes the forces along the contact surfaces. The upper andlower surfaces may be padded or covered by a soft material to minimizetrauma. Both surfaces are separated by posts 4208. Posts 4208 may haveround, elliptical, square or other cross sectional profiles. Posts 4208may be vertically movable or adjustable to change the distance betweenthe upper and lower surfaces. The spacer 4202 may be surgicallyimplanted or more preferably, delivered arthroscopically through acannula and then assembled or expanded in situ. The spacer may have alocking mechanism to ensure stability of the assembly after it has beenpositioned. In some cases, it may be advantageous to overinflate thedistraction balloon to distract the joint even further, thus providingadditional space for delivery and placement of the spacer 4202. Thedistraction device can then be deflated once the spacer is in place.Removal of the spacer 4202 can be accomplished by reintroducing andexpanding the distraction device enough to allow the spacer 4202 to beremoved from the joint space. Alternatively external distraction may beused to insert or remove the spacer.

Referring back to FIGS. 4E-4F, with balloon 414 in place and the jointdistracted, the joint may be manipulated to obtain optimal visibilityand access to the target structure in the joint. Such manipulation mayinclude flexion (bending of the femur anteriorly and superiorly) andextension (straightening) of the hip joint, lateral (external rotationaway from the center of the body) and medial (internal rotation towardthe center of the body) rotation, as well as abduction (lateral movementaway from the body midline) and adduction (medial movement toward thebody midline) of the joint. The size, shape and curvature of theexpanded balloon will permit manipulation of the hip joint in thedistracted configuration without significant movement or dislodgement ofthe balloon. In an exemplary embodiment the balloon will be anon-bifurcated compact shape with a uniformly convex, preferablyspherical, outer surface, positionable in the center of the joint (e.g.fossa) such that contact with the joint surfaces in concentrated withina central region of the joint, allowing the surfaces around the balloonnear the periphery of the joint to be unconstrained. This shape providesa fulcrum about which the opposing bones can rotate and minimizes anyimpedance of joint movement. Additionally, the knee 504 may be flexed orextended to allow greater range of motion in the hip joint. Typically,the hip may be rotated laterally up to at least about 30°, rotatedmedially up to at least about 40°, extended up to at least about 20°,flexed up to at least about 140°, abducted up to at least about 50° andadducted up to at least about 30°. With the knee bent and the hipflexed, lateral rotation may be increased up to about 50°, abductionincreased to about 80° and adduction decreased to about 20°. FIG. 7illustrates flexion F, extension E, medial rotation MR, lateral rotationLR, abduction AB and adduction AD of a patient's hip joint. In additionto providing enhanced access to the joint space, manipulation of the hipjoint also relaxes various tissues to allow better access to the joint.For example, flexion of the hip joint releases tension on the anteriorjoint capsule to allow better access to the labrum and other adjacentjoint structures. Thus, the balloon distraction procedure isadvantageous over traditional traction methods of distracting a jointsince under external traction, conventional methods prevent substantialflexion of the hip joint to relax the capsule. Moreover, the presentmethod is also advantageous over conventional distraction methods sinceit allows for additional manipulation of the hip joint while the jointis distracted. Once the hip joint has been distracted and manipulatedover a broad range of motion into a desired position to provide thedesired access to the joint space, a leg brace 502 as illustrated inFIG. 8 may be used to hold the patient's leg in a desired position. Oneend of the leg brace may be attached to the patient's thigh or lowerleg, and the other end attached to a surgical table or other supportstructure. The leg brace may also be free standing or fixed to thepatient's upper body and/or lower leg.

FIGS. 9A-9I illustrate a preferred embodiment of a method for accessingand distracting a hip joint. FIG. 9A is a top view of the hip jointformed by the femur bone having a trochanter T and femoral head FHdisposed in the acetabulum A. The acetabulum has a depressed regionknown as the acetabular fossa AF where the ligamentum teres (notillustrated for clarity) is attached. The joint also consists of thelabrum L and is surrounded by a capsule C. In FIG. 9A, a needle 4002,preferably 17G, having a sharp removable inner core, is placed underfluoroscopic guidance through the capsule into the peripheralcompartment of the joint. An anterolateral or posterolateral port may beused for joint access. The needle is preferably introduced parallel toand touching the femoral neck and generally tangent to the major curveof the femoral head. This helps ensure that the needle is inserted intothe peripheral compartment safely and helps line the needle with thepoint where the labrum and femoral head touch. Once in place, the sharpinner core is removed and FIG. 9B illustrates injection of saline 4004through the needle 4002 into the peripheral compartment in order todistend the capsule and create more working space. A guidewire GW orswitching wire is then advanced through the needle 4002 into the jointspace as seen in FIG. 9C and then the needle is removed, leaving onlythe guidewire GW in place, as illustrated in FIG. 9D. Next, FIG. 9Eshows a cannulated obturator 4008 advanced over the guidewire GW intothe joint space. The cannula 4006 is preferably 5 mm in diameter and isa split cannula. After the balloon is introduced, the split cannula canbe removed and reintroduced alongside the balloon and the same accessport can be used to insert a scope or other arthroscopic tool. Theobturator 4008 is removed from the cannula 4006, and then an introducer4010 is placed into the cannula 4006. The introducer is preferablyfabricated from a polymer so that it does not damage the joint surfacesor other tissue, and is flexible and pushable so that it may be advancedpast the labrum L into the central compartment of the joint space, asillustrated in FIG. 9F. The introducer 4010 may be about 2-4 mm wide andhave a thickness of about 1-3 mm and is sized to receive a balloondistraction device. The introducer may also have a central lumen toallow fluid to be dispersed from the tip. In some embodiments, theintroducer may be pre-shaped to the contour of the femoral neck to easeinsertion.

The introducer 4010 is then advanced along the contour of the femoralneck under the labrum L until the vacuum seal between the labrum L andfemoral head FH is broken. The tip of the introducer 4010 may be flat inorder to help it pass under the labrum. Slight manual traction ormanipulation to the hip joint may be applied in order to help theintroducer pass under the labrum. Fluid from the introducer may also beinjected to help crossing the labrum. The saline 4004 injected into thejoint space may also include a surfactant to help ease entry of thefluid into the central compartment in order to break the vacuum seal.Once the seal of the labrum L and femoral head FH is broken, theintroducer 4010 is advanced until its tip is within the centralcompartment of the joint as seen in FIG. 9G. Advancement of theintroducer may be visualized under fluoroscopy to help with guidance.The distraction device 4012 having an expandable balloon 4014 near itsdistal end is then advanced through the introducer 4010 into the centralcompartment and the introducer 4010 is removed. The balloon distractiondevice 4012 optionally may also have a stiffening shaft 4016 or metalstylet the help provide stiffness to the device during advancement. Thestiffening shaft 4016 is advanced within a lumen in the distractiondevice 4012 until the distal end of the stiffening shaft 4016 ispositioned at the edge of the central compartment while the deflatedballoon 4014 is advanced into the central compartment, as illustrated inFIG. 9H. The balloon 4014 is advanced to a desired location in the jointspace, preferably the fossa AF. The metal shaft 4016 is then removed andthe balloon 4014 is inflated to distract the joint as illustrated inFIG. 91. Preferably the joint is distracted about 10-12 mm, which may infact actually require the balloon to be expanded to a greater diameter,e.g. 17 mm or more, due to the concavity of the fossa and thedirectional nature of the distraction forces.

For example, FIG. 10A illustrates expanded balloon 4102 distracting ahip joint along vector 4104 which is generally orthogonal to theacetabulum and also orthogonal to the femoral head. When vector 4104 isbroken down into its horizontal 4108 and vertical 4106 components asshown in FIG. 10B, it is clear that the actual horizontal or verticaldisplacement will be much less than total displacement along vector4104. Thus, in order to obtain a desired vertical or horizontaldisplacement of the joint, the joint must be distracted an even greateramount orthogonal to the joint surfaces. Simple trigonometry may be usedto calculate the components of the distraction vector 4104. In addition,the distraction balloon may be deflated and moved within the joint spaceand reinflated in order to provide a different distraction force vectorwhich would result in a different amount or direction of thedistraction.

The distraction balloon may have various shapes and/or features to makeit susceptible to seating and being retained in the fossa. For example,in FIG. 11A, balloon 606 has a overall total axial length which includesthe working length 602 plus the length of the proximal and distaltapered regions. The working length 602 is the portion of the balloonwhich contacts the joint surface and does not include the tapers. Theballoon has expanded diameter 604, preferably about 15-30 mm, morepreferably about 20-27 mm. The working length 602 is preferably in therange of about 0.8 to 1.3 and more preferably in the range of about 0.75to 1.25 times as large as the diameter 604, and in a particularlypreferred embodiment the length is substantially equal to the diameter.This results in a short, generally cylindrical, fat balloon 606 whichallows seating in the fossa and because of its compact size, alsopermits visualization and access around the entire balloon to thesurfaces of the joint behind the balloon. This shape also helps toensure that the entire balloon can be advanced distally from theintroducer sheath or access cannula (if used) within the limited jointspace.

Balloon 606 is mounted to a catheter shaft 608 having a short distal tip614. The balloon may be made of various materials, preferably inelastic,so that the balloon is non-compliant or semi-compliant and inflated to agenerally fixed volume. Possible materials include Nylon, PET,polyurethane, or more compliant materials such as silicone or latex.Balloon wall thickness will preferably range from 0.0013″ to 0.0020″.The distal tip 614 may be a soft durometer polymer to prevent damage tothe joint tissue. Other possible tip configurations which may be usedwith this embodiment or with any of the balloon embodiments disclosedherein are disclosed in further detail below. Shaft 608 may have asingle inflation lumen or more preferably shaft 608 has at least twoparallel lumens, one for balloon inflation 612 and a second lumen 610for a guidewire, fluid infusion or passage of other instruments. Theshaft may also have concentric lumens. A cross-section of shaft 608taken along the line A-A in FIG. 11A is illustrated in FIG. 11B and FIG.11C shows a perspective view of the balloon in FIG. 11A. FIG. 11Dillustrates contact area 652 of this embodiment taken along a plane 654.

In a similar embodiment, instead of a cylindrically shaped body, theballoon is spherically shaped or near spherical. FIG. 11E illustrates aspherically shaped balloon 606 a that has similar dimensions as theembodiment of FIG. 11A. Preferably the radius of curvature issubstantially equal to or less than the radius of curvature of the jointsurface. In the case of a hip joint, the acetabulum has a radius ofcurvature in the range from about 8 to 16 mm. Thus, the balloon engagesthe acetabulum in a single continuous region, preferably centered on thefossa.

FIG. 12 illustrates another embodiment of a distraction balloon. In FIG.12, balloon 704 has a semi-spherical, half-oval or mound shaped superiorregion 708 and an opposing substantially flat inferior region 710. Theinferior region 710 may also have a significantly larger radius than thesuperior region, thereby resulting in a relatively flatter inferiorregion relative to the superior region. The balloon 704 may bestructured so as to preferentially expand in an upward direction whilethe opposing inferior side remains relatively flat or of larger radiusof curvature. The more bulbous, smaller-radius superior side is adaptedto seat in the fossa while the inferior flatter side engages the femoralhead. Balloon 704 is attached to shaft 702 which may have a singleinflation lumen or may have any of the multilumen configurationsdescribed herein. The distal tip 706 is preferably a soft tip, but couldalso include any of the tip embodiments disclosed herein.

FIGS. 13A-13C illustrate still another embodiment of a distractionballoon. In FIG. 13A, the balloon includes a superior portion 804 and aninferior portion 806. The overall balloon is shaped like a fried egg ora flying saucer. The superior portion 804 has a central dome or centralbulbous chamber and the inferior portion 806 is an annular, or donutshaped region surrounding or partially surrounding the central dome.Preferably, the superior portion 804 may be inflated independently ofthe inferior portion 806 and thus the two portions are fluidly isolatedfrom one another by internal membranes in the balloon and thus at leasttwo inflation lumens will be provided in the shaft 802. Alternatively,the two portions may be inflated together, in which case they arefluidly interconnected with one another and only a single inflationlumen is required in shaft 802. The superior and inferior regions mayhave a symmetrical shape both upward and downward, or either or bothregions may have a flatter bottom side and a more rounded and distendedupper side when inflated, with the upper side being adapted to conformto the concave surfaces of the fossa and acetabulum. The central chamberis sized and shaped to settle in the fossa while the annular portion isadapted to engage the joint surfaces surrounding the fossa, therebystabilizing the balloon within the fossa. The catheter shaft may alsohave a soft atraumatic tip 808 or any of the tips disclosed herein. FIG.13B illustrates a top view of the distraction balloon catheter of FIG.13 A and FIG. 13C illustrates a cross-section of shaft 802 taken alongline A-A in FIG. 13A. In FIG. 13C, shaft 802 has three pie shaped lumens810, 812, 814. Two of which may be used to inflate and deflate thesuperior 804 and inferior 806 portions of the balloon and the thirdlumen may be for a guidewire, irrigation or for other instruments.

FIGS. 14A-14B illustrate yet another embodiment of a distraction ballooncatheter. In FIG. 14A, the balloon includes a pancake or discoid shapedor lollipop shaped main body 906 with a longitudinal ridge or tubularchamber 904 extending axially along the superior side of the main body906. In alternative embodiments, the inferior surface of the main bodymay also include a longitudinal ridge or tubular chamber extendingaxially therealong. The ridge protrudes from the surface of the mainbody to facilitate seating of the balloon in the fossa. As in otherembodiments, the main body 906 may be inflated together with orindependently of the tubular chamber 904. The balloon is attached to thedistal portion of a shaft 902 and includes a soft atraumatic tip 908.The shaft may have any of the lumen configurations described herein andthe tip may include any of the tip configurations described herein. FIG.14B is a top view of the balloon depicted in FIG. 14A.

FIG. 15 illustrates another exemplary embodiment of a distractionballoon. The balloon 1006 is asymmetrically tapered and has an almond orteardrop shape. The balloon may have a distal taper 1008 that isdifferent than the proximal taper 1010. In preferred embodiments, theproximal end of the balloon has a shallower taper and the distal end hasa steeper taper. The distal end of the balloon may also be rounded andconvex when inflated as shown in FIG. 16. This shape helps seat theballoon in the fossa. The shallower proximal taper is preferably in therange of about 10 to 45 degrees while the distal taper is preferably inthe range of about 30 to 90 degrees. The shaft 1002 and the distal tip1004 may include any of the features disclosed in this specification.FIG. 16 illustrates another embodiment of a distraction balloon having aconvex distal end. In FIG. 16, the distal balloon walls 1104 are evertedinto the balloon and the exterior surface of the balloon is attached tothe shaft 1102 thereby forming a convex distal region 1108 on theballoon when inflated. One advantage of this configuration is that iteliminates the distal taper on the balloon so that the working surfaceof the balloon which engages the joint surfaces is very close to thedistal tip of the catheter without needing extra length to accommodate adistal taper. Optionally, any of the distal tip or shaft featuresdisclosed herein could easily be used with this balloon configuration.In still other embodiments, the proximal and distal tapers may bereversed. For example, FIG. 17 illustrates an embodiment where thedistal taper 1202 is shallower than the proximal taper 1204. The balloonis mounted to shaft 1206 having distal tip 1208 which may be any of thetips disclosed herein. The ranges of the proximal and distal taper aresimilar to those disclosed above, but they are reversed. This embodimentmay have the advantage that as the balloon inflates it may tend to pushitself distally until the proximal portion with the largest diameter isseated in the fossa. This leaves the anterior portion of the jointunoccupied by the balloon so as to provide maximum space forvisualization and instrument access.

FIG. 18 illustrates a donut shaped balloon 4302 coupled to the distalportion of a shaft 4304. The central depressed region 4306 of the donutis advantageous because it provides an even contact surface fordistributing forces and seating of the femoral head which helps tostabilize the balloon in the joint space. Additionally, the outer convexsurface 4308 of the donut similarly provides a ring of contact todistribute forces and help stabilize the upper surface against theacetabulum. FIG. 19 illustrates an embodiment similar to that of FIG.18, except that the balloon 4404 is shaped like a life preserver or ringbuoy and has an aperture 4406 extending all the way through the centralportion of the balloon. The balloon 4404 is coupled to shaft 4402 andthe distal tip 4408 is flared outwardly and flattened to provide a wideand thin leading edge to facilitate advancement through the joint space.FIG. 20 also illustrates a life preserver or ring buoy shaped balloon4504 attached to a shaft 4502. This embodiment includes a webbed region4506 within the center of the balloon. The distal tip 4508 is also aflattened flared region. The webbed region 4506 allows an articularsurface to be isolated from the remainder of the joint and thuspolymeric material may be delivered thereto and polymerized by light orheat or other means in order to help repair the surface. Alternatively,a bioactive material such as chondrocytes, mesenchymal stem cells,growth factors, etc. or other therapeutic agents may be delivered to theisolated region to stimulate healing.

Some balloon embodiments not only distract the joint, but also isolateportions of the joint to create a dry field which facilitatesvisualization or repair of tissue. For example, FIG. 21A illustrates atoroidal or donut shaped balloon 1302 that can encircle an open centralarea. When the balloon is inflated in the joint, the upper and lowerballoon surfaces engage and seal the surfaces of the joint such that thecentral region 1318 is fluidly isolated from the remainder of the joint.The toroidal shaped balloon 1302 is preferably attached to the shaft1308 in such a way as to facilitate introduction of instruments,therapeutic agents or other materials into the isolated area 1318 whilethe balloon is inflated. For example, the balloon 1302 may be attachedto shaft 1308 such that the central axis of the toroid is perpendicularto the longitudinal axis of the shaft (similar to a candy lollipop) andthe shaft 1308 may extend across the width of the balloon with a distalatraumatic tip 1310. The shaft 1308 has multiple lumens and distal ports1304 in the isolated area 1318 through which devices, fluids, or othermaterials may be introduced into the isolated area. At least one lumenis used to inflate the balloon 1302 through an inflation port 1306. FIG.21B illustrates a cross-section of shaft 1308 taken along the line B-Bin FIG. 21A and shows three lumens 1312, 1314, 1316 which may be coupledwith the inflation port 1306 and the other ports 1304. FIG. 21Cillustrates a cross-section of the balloon 1320 taken along line A-A inFIG. 21A.

FIG. 22A illustrates an alternative embodiment of a distraction balloonthat isolates a region of the joint and provides a barrier against fluidentry. In FIG. 22A, a similar toroidal or donut shaped balloon 1402 isattached to a shaft 1410. However, in this embodiment, the distal end ofthe shaft is coupled to the balloon such that a distal port 1406 isdisposed in the isolated region 1404 of the balloon (the center of thetoroid). Thus, fluids, instruments or other materials may be deployedfrom the catheter shaft tip into the isolated region. Shaft 1410 mayhave multiple lumens, one lumen 1414 for balloon inflation with aninflation port 1408 that exits the shaft under the balloon and at leasta second larger lumen 1412 for passage of the instruments or othermaterials. FIG. 22B illustrates a cross-section of shaft 1410 takenalong the line A-A in FIG. 22A. An additional advantage of thisembodiment is that the distal shaft tip is protected by the balloon andtherefore the shaft is less likely to cause tissue damage duringdelivery of the shaft into the joint space.

An alternative embodiment of a distraction balloon may have a dome shapein order to create an isolated hollow space surrounded by the dome whenthe balloon is inflated. FIG. 23A shows the dome shaped balloon 1502coupled to shaft 1502. Instruments, fluids or other materials may bedelivered from the distal port 1510 of shaft 1502 into the hollow space1506 within the dome. Shaft 1502 also has an inflation lumen withinflation port 1508 fluidly coupled with the balloon 1504 to allowinflation thereof. FIG. 23B shows a cross-section of the distractionballoon taken along the line A-A in FIG. 23A. The upper surface of thedome may also be shaped to match the contour of the fossa, thus wheninflated, the dome conforms to the fossa, helping to stabilize theballoon in the joint space. FIGS. 25A-25B illustrate another embodimentof a dome-shaped distraction balloon. Balloon 4702 is shaped like a bellor dome having a concave region 4706. FIG. 25 A illustrates aperspective view of the balloon 4702 and FIG. 25B shows a midlinesection view of FIG. 25A.

FIG. 24 illustrates yet another embodiment of a distraction balloon.Balloon 4602 is ellipsoidal or oval-shaped and is coupled to shaft 4604and optionally has a flat flared tip 4606. The ellipsoidal balloon maybe symmetrically shaped about the longitudinal axis of the cathetershaft, or it may be flatter on the upper or lower surface.

FIGS. 26A-26B illustrate a multi-element balloon distraction devicehaving three expandable balloons. An upper balloon 4804, a middleballoon 4808 and a bottom balloon 4810 are coupled to shaft 4802.Various tips 4806 such as a flat flared tip may be placed on the distalend of the device or any other the other tips disclosed herein may beused. Each of the balloons 4804, 4808, 4810 may be inflatedindependently of one another or simultaneously. Additionally, eachballoon may have a unique shape or size from the other balloons, or theymay all be the same size. The balloons may be made from the samematerial or each balloon may be made from a different material toprovide variable material properties. Having multiple balloons on thedevice allows the balloons to be independently inflated to fit the jointspace and optimize the direction of distraction, and also has the addedbenefit of still maintaining joint distraction even if one of theballoons bursts. FIG. 26A is an end view of the multiple balloon deviceand FIG. 26B is a side view. Additionally, multiple balloons on thedevice allow the joint to be distracted varying amounts and at differentlocations in the joint to distract the joint in different directions.

In still another embodiment of a balloon distraction device, FIGS.27A-27C illustrate a forked balloon. In FIG. 27A, the opposable balloonelements 4904, 4906 biased outwardly away from each other and areconstrained by an outer shaft 4902. The outer shaft 4902 is retracted inFIG. 27B to expose the opposable balloons 4904,4906 and in FIG. 27C bothopposable balloon elements 4904, 4906 are expanded. The balloons may beconnected to a common inflation lumen or to independent inflationlumens. The forked embodiment allows the device to be inserted into ajoint space such as the hip each of the balloons 4904, 4906 may beplaced on opposite sides of the ligamentum teres to provide adistraction force on both sides of the ligamentum teres.

FIGS. 28A-28B illustrate another embodiment of a distraction device. Anelongate, sausage shaped balloon 5002 is coupled to a shaft 5004 havingan actuation mechanism 5006, as shown in FIG. 28A. Actuating theactuation mechanism 5006, here by retracting a cable coupled with thedistal end of the shaft, causes the balloon 5002 and shaft to curl upinto a toroidal or semi-toroidal shape as seen in FIG. 28B. Theactuation mechanism may then be locked in place to maintain the toroidalshape in use. Alternative embodiments will have a coupling mechanism onthe tip of the shaft (not illustrated) that releasably couples with theshaft proximal to the balloon when in the toroidal configuration.

One of skill in the art will recognize that any of the balloonembodiments may include radiopaque markers on the balloon or the shaftto help with visualization during a distraction procedure. It will alsobe appreciated that other balloon shapes may be used for jointdistraction and therefore the present invention is not limited to theexemplary embodiments disclosed herein.

In addition to using balloon geometry to help the balloon seat in thefossa space, balloon surface coatings and features may also be employed.For example, surface features such as bumps, projections, or ridges maybe added to one facet or multiple facets including opposing upper andlower facets or on all surfaces of the balloon. For example, in FIG.29A, balloon 1602 includes bumps 1604 on the outer surface, while inFIG. 29B the outer balloon surface 1602 has been textured 1606, and inFIG. 29C, ridges 1608 have been added to the outer surface of theballoon 1602. Additionally, the outer balloon surface may be coated witha sticky layer of material to help it remain in the joint space. Any ofthese features may be used in combination with any of the balloonembodiments disclosed herein.

It may also be important for a physician to be able to see through theballoon and be able to view regions of the joint behind the balloon,typically using an arthroscope. The balloon therefore will preferably beinflated with an inflation fluid which is translucent. Furthermore, theballoon may be constructed of materials which have a refractive indexapproximately the same as that of the inflation fluid and/or that of thefluid in the joint space. The balloon may also be coated with a materialthat reduces reflection and enhances translucency. The shaft of theballoon catheter may also include a fiber optic or other light source atits distal end to allow lighting of the joint space. The light sourcemay be within the interior of the balloon, or may be external to theballoon, either proximal or distal to the balloon. FIG. 30 schematicallyillustrates an exemplary embodiment of a balloon 3304 attached to acatheter shaft 3302. A fiber optic 3308 extending through shaft 3302delivers light from a light source 3306 external to the patient, whichmay be a laser, LED, or other suitable light source, to the ballooninterior 3310 where the light is emitted to illuminate the joint. Theballoon or the shaft may also have other features to facilitate jointrepair. For example, in FIG. 31 a femoral head FH has fractured 5702away from the rest of the femur. Physicians typically repair this typeof fracture by drilling a hole and inserting a screw or rod along theline 5704 through the femur into the femoral head. If the hole or thescrew or rod are advanced too far into the bone, the drill bit or thescrew or rod could protrude from the femoral head damaging the surfaceof the acetabulum or other adjacent tissues. Thus, a balloon 5708mounted on a shaft 5706 and having a sensor 5710 within the balloon ornear the distal end of the shaft may be used to detect when the drill orthe rod or screw is about to penetrate the femoral head. The sensor 5710may be an ultrasound, infrared, magnetic, capacitance, or suitablesensor. Alternatively an ultrasonic imaging device may be mounted to theshaft 5706 in or near balloon 5708 to enable ultrasonic imaging of thejoint space or surrounding tissues.

Balloon profile is also important during delivery and during removalfrom the joint. Because the joint space is particularly tight beforedistraction, it is desirable to provide a balloon with the lowestdelivery profile possible. The balloon may be shaped and have pleats,folds, or other features to help it collapse to a minimal profile upondeflation to facilitate introduction and withdrawal. In addition tocarefully folding the balloon over the shaft and delivering the balloonsheathed, other mechanisms may be employed to help maintain a lowprofile. The proximal and distal ends of the balloon may be coated witha lubricious low-friction coating to facilitate retraction of theballoon into a cannula, sheath or other access device. Other mechanismsactively collapse the balloon. For example, in FIG. 32A, the catheterincludes an inner shaft 1704 and an outer shaft 1706 disposed over theinner shaft 1704 and rotatable relative thereto. The distal end of theballoon 1702 is attached to the inner shaft 1704 and the proximal end ofthe balloon 1702 is attached to the outer shaft 1706. Rotation of theouter shaft relative to the inner shaft twists balloon 1702 as seen inFIG. 32B. Thus balloon 1702 is tightly and helically wrapped around theshafts as shown in FIG. 32C resulting in a minimum profile.Additionally, the twisting motion helps evacuate substantially all ofthe inflation fluid from the balloon, further reducing the deflatedprofile. An actuator mechanism may be included on the proximal end ofthe shafts that can be actuated by a physician to perform the shaftrotation. FIG. 33 illustrates an exemplary actuator mechanism. In FIG.33, a proximal handle has two sections 3602 and 3604. One section isoperably coupled with the inner shaft and the other section is operablycoupled with the outer shaft. Rotation of one section relative to theother will result in rotational along the shaft and wrapping of theballoon 3610.

FIG. 34 illustrates an alternative embodiment where instead of rotatingthe inner shaft relative to the outer shaft, the inner shaft 1704 isslidable distally relative to outer shaft 1706 such that the proximaland distal ends of the balloon may be separated to apply tension to theballoon 1702. Again, the shafts may be controlled with an actuatormechanism on the proximal end of the inner and outer shafts. Thisstretches the balloon longitudinally so as to minimize balloon profile.FIG. 35 illustrates an exemplary actuator mechanism on a proximal handle3502. Movement of slide 3508 will result in relative movement of theouter shaft 3608 with respect to the inner shaft, resulting in thedesired tension in balloon 3506. Thus linear movement or rotation of theshaft can be used to actively collapse the balloon.

FIG. 36 illustrates still another embodiment where the balloon islinearly stretched. In FIG. 36, a compression spring 1902 is disposedbetween the inner 1704 and outer shafts 1706. The spring 1902 is biasedin an elongated configuration so that the inner shaft is biased to movedistally relative to the outer shaft, again stretching balloon 1702 andreducing its profile. Upon inflation of the balloon, the balloonradially expands and this force is high enough to overcome the springforce and retract the inner shaft 1704 relative to the outer shaft 1706thereby permitting balloon expansion. Additional details on similarmechanisms are disclosed in U.S. Pat. No. 7,488,337 to Saab which isincorporated herein by reference. In other embodiments, instead of alinear spring, a torsional spring may be used. In addition, the balloonmay be attached to the shaft so as to be normally in torsion or intension when deflated so that it preferentially exists in a collapsedconfiguration which is overcome during inflation. Upon deflation, theballoon returns to its collapsed configuration.

A deflated balloon may also be constrained by rolling it into a lowprofile configuration and constraining it with a sheath. The sheath maybe retracted after the balloon has been delivered to a target site andthe balloon may be expanded. FIGS. 37A-37B illustrate an alternativeembodiment where the constraining sheath 5104 is perforated along line5106. A shaft 5108 carries the balloon 5102 which is maintained in arolled up, low profile configuration by sheath 5104. Once the balloon isdelivered to the target site, it is inflated. Inflation of the balloon5102 forces the sheath to tear along the perforation 5106, allowing theballoon to fully expand as seen in FIG. 37B.

Catheter tip configurations are also an important feature of the ballooncatheter. The tip should be configured so that it can be passed into andthrough the joint without getting hung up or damaging joint tissue andbone structures. In particular, the tip should be adapted to passthrough the joint without the tendency to go into the fossa where it mayengage the fossa walls or ligamentum teres and become obstructed fromfurther advancement. The tip should also be adapted to allow the entireballoon to enter the joint and to be seated in the fossa withoutundesirable engagement with the posterior articular joint surfaces. Thetip will preferably be flexible, usually more flexible than the rest ofthe catheter shaft. Also, the tip is preferably resilient so that whenit has a pre-defined shape, the tip will return to this unbiased shape.Thus the tip preferably extends no more than 10 mm, and more preferablyno more than about 5 mm, beyond the distal end of the balloon when thetip is straightened. FIG. 38A illustrates a straight tip 2004 on the endof shaft 2006 having a balloon 2002. FIG. 38B illustrates across-section of the tip 2004 taken along the line A-A in FIG. 38A. FIG.39A illustrates a tapered or conical tip 2102. FIG. 39B illustrates across-section of tip 2102 taken along line A-A in FIG. 39A. In someembodiments, the tip may be tapered only on two opposing sides so itmore readily bends about a preferred transverse axis. FIG. 39Cillustrates a cross-section taken along line A-A in FIG. 39A when thetip includes a taper only on two opposing sides 2104 so that it moreeasily bends about a vertical transverse axis than about othertransverse axes. FIG. 40A illustrates another embodiment having aspherical or bullet shaped tip 2202 with a blunt atraumatic distal tipand FIG. 40B illustrates a cross-section taken along line A-A in FIG.40A. In other embodiments, the tip may have a curve, J-shape, or pigtailshaped. FIG. 41 illustrates a balloon 2304 coupled to a shaft 2302having a pigtail tip 2306. The pigtail 2306 may be straightened out bypassing the catheter over a guidewire GW extending through a lumen inthe tip, or a stylet may be positioned in a lumen of the shaft and tip.FIG. 42A illustrates a tip 2406 having a slight curve in it.Additionally, the shaft 2402 has a cross-sectional width greater thanits cross-sectional height, as seen in FIG. 42B which is a cross-sectiontaken along line A-A in FIG. 42A. This configuration preferentiallyallows the shaft to bend transverse to the width since the upper andlower sections are less stiff than the side sections. The tip 2406 isoptionally pre-curved about an axis parallel to that about which shaft2402 bends more easily. With this structure the device is adapted topass through the curved space between the ball and socket of a jointwith minimal engagement with the joint surfaces. Balloon 2404 isattached to shaft 2402 which may have the same cross-sectional profileor another profile such as round, square, rectangular, oval or any otherprofile. Any of these tip configurations described above may be combinedwith any of the other balloon embodiments or other features disclosedherein.

In addition to various cross-sectional geometries, the catheter shaftitself may have features which will facilitate its introduction into thejoint space. In particular, the hip joint is challenging due to itscurvature and depth and surrounding tissue, including ligaments, andtendons that must be penetrated. In one exemplary embodiment, the shaftmay have a precurved shape to facilitate such introduction. FIG. 43illustrates a balloon 2506 attached to a shaft 2502 having a precurvedregion 2504 and a tapered distal tip 2508. The shape of the curve region2504 depends on the desired access location relative to the position inthe joint where the balloon is to be placed, such as the fossa in a hipjoint. In FIG. 43, a distal section of the shaft approximately 25 to 50mm from the distal end has a curve with a radius approximately the sameas the radius of curvature of the acetabular socket. The radiuspreferably substantially matches that of the socket, but may vary byplus or minus 20%. Additionally, in this embodiment, a stylet may beremovably positioned in a lumen of the shaft 2502 in order totemporarily straighten out the curved portion during delivery, asillustrated in phantom in FIG. 43.

The shaft will usually have a lumen for inflation of the balloon.Additionally, the shaft may have a guidewire lumen so that the shaft maybe advanced over a guidewire into the joint. The guidewire lumen mayextend the full length of the catheter shaft or an exit port may beprovided between the balloon and the proximal end of the catheter,usually in the distal half of the catheter, to allow easier placement ofthe catheter over the wire. For example, FIG. 44A illustrates aconventional over-the-wire configuration where the shaft 2602 has aninflation lumen and a guidewire lumen extending the entire length of theshaft. The guidewire GW exits from a distal port on the catheter tip.The guidewire passes through the interior of balloon 2604 on the distalend and through a connector hub 2606 on the proximal end. FIG. 44Billustrates an embodiment where the guidewire exits a port 2608 that iscloser to the balloon 2604 and the distal end than it is to the proximalcatheter end. This configuration is sometimes referred to as rapidexchange.

A stopping element may also be coupled with the guidewire in order toprevent over-extension of the guidewire beyond the distal tip of theshaft to a point where the guidewire could damage joint tissues distalto the shaft and balloon. In FIG. 44C, stopping element 2610 is anelastomeric or metallic ball frictionally fit over or otherwise attachedto the guidewire GW. It could also be a collet or other device that canbe attached to the guidewire a predetermined distance from the wire'sdistal end and that has a size larger than the guidewire lumen so thatit cannot pass into the guidewire lumen. The stopping element ispreferably detachable from the guidewire with a set screw or otherreversible clamping means to secure it to the wire at the desiredposition.

The shaft may also have a lumen to receive a stylet for supporting theshaft and enhancing its column strength. The lumen could be a sharedlumen, e.g. shared with the guidewire lumen or the inflation lumen, orthe catheter may have a separate stylet lumen. The lumens may be coaxialwith one another or parallel. For example, FIG. 45A illustrates aballoon 2702 attached to a catheter shaft 2710 having a ballooninflation lumen 2708 and a stylet lumen 2712. The stylet lumen 2712extends into a garage or pocket 2706 in the distal tip 2704 of thecatheter. Thus, the stylet may be advanced until it bottoms out in thepocket 2706. The stylet may have a round cross-section or it may berectangular or oval so that it bends preferentially about one axis.Additionally, the distal tip of the stylet may be keyed to the pocket2706 so that the two are releasably coupled together and rotatablyinterlocked. For example, a stylet 2714 may have a flat distal section2716 which fits in pocket 2706. This allows the stylet to be rotatedwhich will also correspondingly rotate the distal catheter tip. Thisallows the distal end of the balloon to be twisted relative to itsproximal end when deflated so as to helically wrap the balloon,minimizing profile. FIG. 45C illustrates the tip of stylet 2714 having akeyed tip 2716. In this embodiment, the tip 2716 is flat like ascrewdriver, but one of skill in the art will appreciate that many othertip geometries may be employed, such as a square or cross shape to fitinto a pocket of complementary shape. The stylet will have sufficientflexibility to allow deflection into a curved configuration as thecatheter is inserted and advanced into the joint space. In addition tostraight stylets, the stylet may also be pre-shaped into a curve tofacilitate introduction. The stylet may also include a series ofparallel transverse cuts or slots 2718 along a portion of its length toenhance bending in one or more directions, as illustrated in FIG. 45D.The slots may be symmetrically arranged on four opposing sides of thestylet so that the stylet bends symmetrically in the four directions orthe slots may be located on only one side or two opposing sides so thatthe stylet bends more easily about one axis or in one or moredirections.

The shaft may also be configured to collapse to a flat configurationwhen the lumens are evacuated, minimizing its profile and the space thatit occupies in the joint. This allows the shaft to be flattened when theballoon is deflated so as to minimize any distraction of the joint orinterference with joint movement, allowing the physician to leave theballoon in place and manipulate the joint. For example, in FIG. 46A,shaft 2802 has a round profile when an inner lumen 2806 is filled with astylet 2804, inflation fluid or a guidewire. Once the stylet 2804 isremoved, the shaft collapses into an oval or flattened shape. FIG. 46Billustrates another embodiment wherein the shaft 2808 has two lumens2810 and 2812. When stylet 2814 is positioned in lumen 2812, the shafttakes its expanded oval or rectangular cross-sectional shape and whenstylet 2814 is removed, the shaft 2808 takes a flattened oval orrectangular form of substantially reduced cross-sectional height.Preferably the cross-sectional height of the shaft when collapsed willbe less than about one half and more preferably less than about onethird the cross-sectional height when not collapsed. An additionaladvantage of the rectangular shaped shaft 2808 and correspondinglyshaped stylet 2804 of FIG. 46B is that its cross sectional geometryallows it to more easily bend around one transverse axis than aroundothers. This is due to the fact that the shaft width along one axistransverse to the shaft is substantially greater than the shaft heightalong a second transverse axis orthogonal to the first axis. Inpreferred embodiments, the cross-sectional width is at least about 1.5to 5 times the shaft cross-sectional height. In addition to shafts withoval cross-section, shafts with rectangular, racetrack, and otherasymmetrical cross-sections may also be used.

Some catheter embodiments may include steerable features to help directthe catheter as it is being introduced into the joint space. In FIG. 47Aa balloon 2904 is attached to a catheter shaft 2902 having a tapered tip2914. Shaft 2902 has two lumens. A first inflation lumen 2910 is fluidlycoupled with the balloon via port 2912 to allow inflation and deflationof the balloon. A second lumen 2906 allows a pullwire 2908 to slidablyextend from the proximal end of the catheter to a distal portion of thecatheter. The distal end of the pullwire may include a ball or otheranchor 2916 to facilitate its attachment to the distal portion. Inpreferred embodiments, the pullwire 2908 is off-center from the centralaxis of the shaft 2902 so that when the pullwire is retracted, thedistal portion of the shaft will deflect in one direction, as seen inphantom in FIG. 47A, because exerting tension on the wire will deflectthe distal portion through a desired degree of bending. Releasingtension in the pullwire will allow the distal portion to return to itsunbiased straight shape. FIG. 47B illustrates an embodiment where thepullwire 2908 is attached near the distal end 2916 a of the flexiblecatheter tip 2914 so that only the tip bends when the pullwire isactuated. The proximal end of the shaft may include a handle with anactuator mechanism such as rotatable knobs, a trigger or a slidemechanism so that a physician may easily control actuation of thepullwire. Actuators similar to those illustrated in FIGS. 33 and 35 maybe used to move the pullwire.

Because the balloon can encounter sharp or rough areas in the jointspace and the surgical repair procedure performed on the joint ofteninvolves sharp instruments, balloon puncture is a consideration.Therefore, any of the balloons described herein may be multilayered ormay be made from a puncture resistant material or they may includecoatings which resist puncture. Fibers, a mesh or layers of Kevlar,Vectran or other materials of high toughness may be embedded in oradhered to the wall of the balloon. The balloon may have a multilayeredwall to allow higher burst pressures and increase puncture resistance.For example, in FIG. 48A, the balloon has an inner wall 3002 and anouter wall 3004. The outer wall may be the same material as the innerwall and the two bonded together to provide a greater thickness toincrease strength and resist puncture. In some embodiments, the layersneed not be bonded together and may optionally have a lubricant betweenthe layers. Also, either one or both ends of the outer layer may beunattached to the the catheter shaft thereby allowing the ends to floatslightly as the balloon expands, the inflation fluid being contained inthe inner layer, which helps reduce stresses. In an exemplaryembodiment, the inner and outer walls are each about 0.0004″-0.0010″ inthickness. Alternatively the outer wall may be a different, morepuncture resistant material. In other embodiments, the inner and outerwall may be unattached to each other or separated by a gap so if onewall is punctured, the remaining wall will still be intact. FIG. 48Billustrates an inner balloon wall 3002 having a separate layer 3006 of apuncture resistant material.

In addition to enhancing balloon puncture resistance, a balloon shieldmay be used to help protect the balloon from puncture. The shield may bepositioned adjacent to or around the balloon and it may be coupled tothe balloon catheter shaft or the balloon itself, or it may be part of aseparate device independently positionable in the joint. The shieldpreferably is collapsible by folding or winding, similar to thatperformed for the balloon, so that the shield may fit in an arthroscopicport or small incision and may be resilient so as to expand onceinserted into the port. The shield may also be adapted to connect oradhere to the balloon or catheter shaft to help retain its position.FIG. 49A illustrates an exemplary embodiment of a shield. In FIG. 49A aninflated balloon 3106 is attached to a catheter shaft 3106. Disposedover the balloon is a shield 3104 attached to a shaft 3102. Optionally,the shaft may include an eyelet or clip 3108 which allows the shield tobe releasably coupled with the catheter shaft. The shield may have acylindrical curvature and may be a mesh-like material, a solid metal orplastic, or other material which prevents sharp objects from penetratingthe balloon. The shield may be configured to cover only a portion ofballoon 3106 or it may encircle the entire circumference of the balloon.FIG. 49B is a cross-section taken along like A-A in FIG. 49A.

In some embodiments, the balloon may be detachable from the cathetershaft. For example, in FIG. 50A, a balloon 3806 is attached to a shaft3802. An inflation tube 3804 is disposed in a lumen in shaft 3802. Shaft3802 has a coupling 3810 on its distal end which releasably couples to acomplementary feature 3810 a connected to the proximal end of balloon3806. Once the balloon is inflated in the joint space, the shaft may bedecoupled from the balloon either by exerting tension on the shaft or byactuating a mechanism on the proximal end of the device which decouplesthe coupling 3910, 3910 a from the balloon. The inflation tube 3804remains coupled with the balloon 3806 and the shaft is retracted overthe inflation tube. Alternatively the inflation tube may be external andparallel to the shaft 3802. In FIG. 50B, the proximal end of the balloonhas a one-way valve 3808 that eliminates the need for an inflation tube.Thus, once inflated, shaft 3802 may be detached from the balloon 3808and the balloon will remain in the joint space inflated and free of theshaft. FIG. 51A illustrates another embodiment of a balloon distractiondevice that is detachable from the delivery shaft. A balloon 5204 iscoupled to a small, flexible inflation shaft 5202 having an inflationlumen (not illustrated). The inflation shaft 5202 is coupled to a largerdiameter and stiffer delivery shaft 5206 by feeding the inflation shaft5202 through one or more eyelets 5208 on the delivery shaft 5206.Alternatively, the inflation shaft 5202 may be slidably disposed in alumen of the delivery shaft 5206. One of skill in the art will of courseappreciate that other attachment mechanisms may be used to join theinflation shaft 5202 with the delivery shaft 5206. During delivery, thestiffer delivery shaft 5206 is used to help advance the balloon 5204through the joint space. Once the balloon is advanced to the targetsite, the outer delivery shaft 5206 may be retracted and withdrawn fromthe patient, leaving only the balloon 5204 and the inflation shaft 5202in the joint space. FIG. 51B shows separation of the balloon 3806 fromthe delivery shaft 5206. This creates maximum space available for otherinstruments and visualization in the joint space. The balloon may beretracted from the joint space when the procedure is terminated, bysimply pulling on the inflation shaft 5202 or by reintroducing deliveryshaft 5206 over the inflation shaft to assist balloon removal.

In addition to the distraction balloon, a system may include aspecialized inflation device such as the exemplary embodiment in FIG.52. In FIG. 52, inflation device 3202 is fluidly coupled via a flexibletube 3204 to a balloon distraction catheter 3206. The flexible tube 3204may be releasably coupled to the catheter 3206 using Luer connectors3208 a, 3208 b or other common medical device fittings. The inflationdevice may be designed to be hand held, or to be mounted to anintravenous fluid pole or the operating table, or to be placed on theoperating room table or patient's body. For hip distraction, theinflation device should have enough fluid capacity to inflate ballooncatheter 3206 with an inflatable volume of at least 16 milliliters to apressure of 200 psi. The fluid used to inflate the balloon willpreferably be sterile saline, sterile contrast media or a combination ofboth. The inflation device 3202 allows the user to incrementally orfully inflate or deflate the balloon catheter with a push of a button orbuttons 3218 and with single handed operation. For example, theinflation device may comprise a fluid cylinder 3210 and a piston 3212that is driven by an electric motor or hydraulic drive system such thatpiston 3212 is displaced a known distance for each push of a button3218. Thus as the piston moves, plunger 3214 displaces a correspondingvolume of fluid from the reservoir 3210 to the balloon catheter. Onebutton may allow incremental partial balloon inflation with a set volumeof fluid, while a second button inflates the balloon to a fully selectedpressure. A third button withdraws all fluid from the balloon byretracting the piston 3212.

Optionally, the inflation device 3212 will include a mechanism whichpulls a vacuum on the balloon catheter prior to inflation to remove anyair from the catheter. This can be activated by the user with a push ofa button or other single handed means. Performing this step ensures thatthe subsequent inflation will minimize any compressible air presentwithin the catheter and balloon. The “de-airing” mechanism willintroduce a bolus of inflation fluid into the balloon to force any airout of the balloon and inflation lumen. The device may be tilted withthe balloon downward to allow air to escape proximally through theinflation lumen. A vent may be provided on the inflation device incommunication with the inflation lumen to allow the air to escape. Thevent may comprise a three-way stopcock on the inflation lumen which maybe moved to a position that allows escaping air to exit the inflationlumen. The vent may optionally include a one-way valve to prevent airfrom re-entering the system.

The inflation device 3202 may also include a gauge 3216 or other type ofindicator that indicates balloon pressure and/or amount of distraction.In such embodiments the balloon catheter may include a pressure sensorand/or distraction sensor 3220 on or within the balloon which iselectronically coupled to the indicator on the inflation device. Thedistraction sensor may be an optical sensor such an IR sensor to sensethe distance between the joint surfaces and/or the distance to theballoon wall from the shaft. Alternatively the amount of distraction maybe simply calculated based on balloon pressure and apressure/distraction curve created from empirical testing.

Other systems may include an internal distraction device in combinationwith other specialized instruments for performing therapeutic ordiagnostic procedures while the joint has been distracted. For example,FIG. 53 illustrates a system which includes an access port or cannula3402, a balloon distraction catheter 3404, an inflation device 3406, aguidewire 3408 as well as other surgical instruments 3410 including butnot limited to fiber optic lights, retractors, cutters, debriders,microfracture awls, suture anchors, suture holders or suture managers.These may be used to arthroscopically view or distend joint tissue.Diagnostic procedures can be performed as well as therapeutic proceduressuch as debridement, joint flushing or smoothing of joint surfaces andadjacent tissues, and performing other repairs such as that of thelabrum. Microfracture of the joint surfaces may also be performed inorder to stimulate cartilage or other tissue growth.

The invention further provides a system comprising an internaldistraction catheter and a specialized cannula adapted for introductionof the catheter into the joint capsule. The cannula may include aretention device as illustrated in FIG. 54A. While various types ofretention mechanisms are possible, in this embodiment cannula 5302 is atubular shaft which includes two to four, or more (four in thisexemplary embodiment) axial elements 5304 having distal ends which arebiased to deflect radially outward at the distal end of the cannula.Thus, once the axial elements are advanced through the cannula andbecome unconstrained, they deflect outward forming a flanged regionwhich serves as an anchor and prevents the cannula from pulling out andaway from the capsule. A distraction device having a balloon 5308mounted to a shaft 5312 near the distal tip 5310 of the shaft also isinserted into the cannula 5302. The proximal end of shaft 5312 includesa Y-connector 5318 which allows an inflator to be fluidly coupled withthe balloon 5308 and another device, such as a syringe for irrigation tobe fluidly coupled with the inflation catheter. A shoulder 5314 on theproximal end of the cannula 5302 allows the tube to be manipulated by asurgeon and a shoulder 5316 on the proximal end of the retention deviceallows the axial elements 5304 to be advanced from and retracted intothe cannula. FIG. 54B highlights the distal end of the cannula andretention mechanism. FIG. 54C illustrates a cross section of FIG. 54Ataken along line B-B and illustrates that the four axial elements 5304also may be connected with rings 5306 which help bias the axial elementsoutward against the inner surface of the cannula to provide maximumspace for instruments to be passed therethrough. In the embodimentillustrated axial elements 5304 and rings 5306 are removable from thetubular cannula 5302 although in alternative embodiments the axialelements may be permanently attached to the cannula or integrally formedtherewith. The axial elements may be fabricated from a superelastic orshape memory alloy such as nitinol or a spring temper stainless steel orother resilient metal or polymer may be used. Thus, the retention deviceretains the distal end of the cannula in the joint capsule and allowsthe cannula to be as short as possible to provide a clear space distallyin which to work. In addition, traction may be applied to the cannula todistend the capsular ligaments, thereby increasing the space within thecapsule to allow better access and visualization of the joint.

Another embodiment of a system having an internal distraction catheterand a specialized cannula adapted for introduction of the catheter intothe joint capsule is illustrated in FIGS. 54D-54E. The system includes adistraction device having a balloon 5308 mounted to a shaft 5312 nearthe distal end 5310 of the shaft. A Y-connector 5318 or other connectoris used to fluidly couple the balloon 5308 with an inflation device anda second device such as a syringe or irrigation device. The cannula 5302a includes four articulated hinges 5320 that deflect radially outwardforming wings when the cannula 5302 a is axially compressed. A shoulder5314 on the proximal end of the cannula 5302 a allows a surgeon toeasily grasp and manipulate the cannula and a C-ring 5322 serves as alocking mechanism as will be described below. An inner sleeve 5324includes a plurality of wire-like filaments 5326 (here 4 filaments) thatare biased to deflect radially outward when unconstrained. A shoulder5316 on the proximal end of the inner sleeve 5316 allows a surgeon tograsp and manipulate the inner sleeve. In use, the inner sleeve 5324 isadvanced into the central channel of cannula 5302 a. Filaments 5326deflect radially inward as the inner sleeve is advanced into thecannula, until the filaments reach the distal end of the cannula andthen become unconstrained and flare radially outward as seen in FIG.54E. The inner sleeve is then retracted proximally to apply acompressive load against cannula 5302 a which forces the hinges 5320 tobend and expand radially outward forming wings. Thus, two anchorportions are formed—a proximal anchor portion consisting of theoutwardly deflected hinges 5320 and the flared filaments 5326. Thisconfiguration may be used to help anchor the cannula to tissue, such aswhen the filaments are inside the capsule and the hinges are outside thecapsule but under the skin. The C-ring 5322 may be snapped around theinner sleeve 5324 between the two shoulders 5316, 5314, therebymaintaining the separation between the two shoulders and thus keepingthe hinges 5320 deflected radially outward. The distraction device maythen be inserted into the cannula to distract a joint. Once theprocedure is completed, the C-ring may be removed from the inner sleeveallowing the hinges to return to their normal flush configuration withthe cannula. The inner sleeve may also be retracted into the cannula toremove the filaments and allow the cannula to be withdrawn from thecapsule. Embodiments of the cannula with a retention mechanism may alsobe used when tension on the joint capsule is relaxed (e.g. by flexion ofthe joint). This allows the cannula to be pulled outwardly away from thejoint while the retention features are deployed and helps “tent up” thecapsule to provide more space.

Still other embodiments of cannulas which may be used with thedistraction tools disclosed herein include the split cannula seen inFIG. 55A. The cannula includes an upper portion 5402 and a lower portion5406 that are coupled together with a releasable seam 5404 (e.g. aperforation). Once the cannula has been placed into the joint space andthe distraction device or other instruments have been delivered to theirtarget site, the upper portion 5402 may be separated from the lowerportion 5406 and one or both portions removed from the patient as seenin FIG. 55B. In still other embodiments, a C-shaped or half pipe shapedcannula 5502 seen in FIG. 56 may be used and in still other embodimentssuch as in FIG. 57, double barreled cannulas 5602, 5604 may be insertedinto a single portal. Each of these embodiments helps introduce moreinstruments into the joint space using fewer portals or helps moreinstruments to be introduced through a cannula.

While the above is a complete description of the preferred embodimentsof the invention, various alternatives, modifications, and equivalentsmay be used. The various features of the embodiments disclosed hereinmay be combined or substituted with one another. Therefore, the abovedescription should not be taken as limiting in scope of the inventionwhich is defined by the appended claims.

What is claimed is:
 1. An apparatus for distracting a hip joint having afemoral head and an acetabulum with an acetabular fossa, said apparatuscomprising: an elongate flexible member having a proximal end, a distalend terminating in an atraumatic distal tip and a shaft extendingbetween the proximal end and the distal end along a central longitudinalaxis, said shaft including a central lumen extending from the proximalend to the distal end of the elongate flexible member, the shaft isconfigured for moving from a straight configuration when the elongateflexible member is aligned with the first central longitudinal axis anda curved configuration when the elongate flexible member is not alignedwith the first central longitudinal axis; an expandable member extendingthe central longitudinal axis, said expandable member is coaxiallycoupled to the distal end of the elongate flexible member, theexpandable member being fluidly expandable from a collapsedconfiguration to an expanded configuration, the expandable member havinga dimension in a direction transverse to the second central longitudinalaxis of the expandable member of at least about 10 mm in the expandedconfiguration and being configured to apply a distraction force of atleast about 50 lbs. to said acetabulum and said femoral head at apressure of less than about 100 psi; and an actuation mechanism formoving the elongate flexible member between its straight configurationand its curved configuration; wherein the actuation mechanism comprisesa flexible pulling element which is attached to the distal tip of theelongate flexible member and extends proximally back alongside theexpandable member, proximally back alongside a portion of the shaft,passes through a side wall of the shaft into the central lumen and thenextends proximally back within the lumen of the shaft so that when theflexible pulling member is pulled, the flexible pulling member bends thedistal end of the elongate flexible member, and the expandable membercoupled to the elongate flexible member, into a toroidal shape, with thedistal tip of the elongate flexible member releasably coupled to aportion of the shaft of the elongate flexible member proximal to thedistal end of the shaft of the elongate flexible member when in thetoroidal shape, and said flexible pulling element is configured to becoupled in place to maintain said toroidal shape when in use; whereinthe expandable member is configured to engage the acetabulum only withina contact surface such that at least about 50% of the contact surface isdisposed in the acetabular fossa when the expandable member is in theexpanded configuration.
 2. The apparatus of claim 1, wherein an expandedsize and an expanded shape of the expandable member are selected so thatthe expandable member is configured to be biased into the acetabularfossa when expanded.
 3. The apparatus of claim 1, wherein the expandablemember has an outer surface with a radius of curvature of at least about8 mm in the expanded configuration.
 4. The apparatus of claim 1, whereinthe expandable member has an axial length in the expanded configuration,the axial length being no more than about 1.5 times the size of theacetabular fossa.
 5. The apparatus of claim 1, wherein the expandablemember has an axial length and a diameter, and wherein the axial lengthis no more than about 0.8 to about 1.3 times the diameter of theexpandable member when expanded.
 6. The apparatus of claim 1, wherein acontact surface of the expandable member is at least about 200 mm² andless than about 800 mm².
 7. The apparatus of claim 1, wherein theexpandable member comprises a balloon.
 8. The apparatus of claim 1,wherein the distal tip of the elongate flexible member is configured tobe passed into and through the hip joint without causing trauma to thejoint or tissue adjacent thereto.
 9. The apparatus of claim 1, whereinthe flexible pulling element is a pullwire.
 10. The apparatus of claim1, wherein the actuation mechanism further comprises an actuator nearthe proximal end of the elongate flexible member, the actuator operablycoupled with the flexible pulling element.
 11. The apparatus of claim 1,wherein the elongate member is detachably connected with the expandablemember such that the expandable member may be detached from the elongatemember while the expandable member remains in the expanded configurationand seated in the acetabular fossa.
 12. The apparatus of claim 1,wherein the flexible pulling element is a flexible pull line.